1. Field of the Invention
The present invention refers to a claw for a milking machine, comprising a housing having four inlet members, which via four teatcup liners are adapted to connect the housing to four respective teats of an animal to be milked, and an outlet member, which via a conduit member is adapted to connect the housing to a milk collecting member of the milking machine, said housing having a center axis extending through the claw essentially vertically when the claw, in an operating position, is attached to the udder of the animal, said four inlet members being distributed around the centre axis and provided in pairs in such a manner that they are adapted to the natural position of the teats of the udder of the animal, a first pair of the inlet members, which is intended for two front teats of the animal, being directed obliquely forwardly and outwardly and having a different position with respect to the centre axis than a second pair of the inlet members, which is intended for the rear teats of the animal and is directed obliquely rearwardly and outwardly with respect to the centre axis.
2. Description of the Prior Art
Such a claw is known by EP-B-418 260 and comprises a housing, having a center axis which in an operating position of the claw extends vertically, an upper portion and a lower portion. The inner space of the housing forms a chamber for receiving milk via four inlet members connected to a respective teatcup of the milking machine via a short milk conduit. An outlet member, which via a milk conduit is connected to a milk collecting unit of the milking machine, extends from said chamber. Both the outlet member and the inlet members are fixedly provided on the upper portion of the housing and are thus not movable in relation to each other. The outlet member comprises an outlet nipple extending radially outwardly perpendicularly from the center axis of the housing. The inlet members comprise four inlet openings provided in pairs so that one of the pairs is intended to be connected to teatcups being applied to the front teats of the cow and the other pair is intended for teatcups being applied to the rear teats of the cow. The inlet members are provided on a conical surface of the upper portion at the same height with respect to the vertical center axis.
By studying the position of the teats of the udder of cows, it has been recognized that the distance between the two front teats is longer than the distance between the two rear teats. An investigation from 1983 discloses an average distance between the front teats of 150 mm, between the rear teats of 85 mm and between the rear and front teats of 100 mm. Furthermore, it has been recognized that the front udder half is higher than the rear one, i.e. the two front teats are located at a higher position than the two rear teats. When the udders are charged with milk the teats are relatively stiff and straggling and will therefore be relatively immovable in relation to these positions. This situation makes it difficult to attach teatcups configured in a conventional manner to the teats of the cow, since the teatcups do not reach the teats properly and it may therefore be difficult to attach teatcups in such a manner that they close tightly against the teat. If the teatcup liner does not close tightly against the teat, there may be a significant air inlet between the teatcup liner and the teat, which may not be controlled. This deficiency makes the milking less effective and requires a higher capacity of the vacuum pump and it may in certain situations lead to detachment of the teatcups before the milking has been terminated. The milk conduits may also not be arbitrarily long, since the claw in such a case will touch the ground or the floor, at least during the end of the milking. The problems mentioned above have become worse in recent time, since the short milk conduit has become thicker and thus stiffer in order to be able to conduct an increasing milk flow. Furthermore, it has been difficult to provide a close connection between the short milk conduit and the housing of the claw due to the bending forces acting on the milk conduit. Because of this, air tends to penetrate the inner space of the housing between the short milk conduit and the inlet opening.
SE-B-449 154 discloses a milking machine having a claw comprising a housing with an upper portion and a lower portion. Four inlet nipples are provided on the upper portion and connect the inner space of the housing to a respective teatcup of the milking machine via conduits. Four outlet nipples are provided on the lower portion and connect the inner space of the housing to a milking collecting member of the milking machine via conduits. In the inner space of the housing there are four intermediate walls dividing the inner space of the housing in four chambers of equal size. One inlet nipple and one outlet nipple is in connection with each chamber. The upper portion may be rotated in fixed 90.degree.0 steps in relation to the lower portion so that each inlet nipple may be displaced to be opposite another outlet nipple.
U.S. Pat. No. 2,775,225 and U.S. Pat. No. 2,429,983 both disclose a claw provided with four inlet nipples provided in pairs and adapted to the position of the teats of the udder. These documents do not teach how to configure a passage through the wall of the claw in order to be able to receive a teatcup liner.
FR-A-1 158 460 discloses a quite different type of claw having four inlet nipples, all directed in essentially the same direction. Each nipple is mounted in a passage extending through an essentially plane wall portion of the claw. The teatcup liners are adapted to be mounted on the nipples in a conventional manner.